Investigation On Active Structural Acoustic Control Of Diesel Engine Noise Enclosure

Diesel engine is widely used in various ships and vessels due to the low fuel consumption,high reliability,low gas emissions,effortless installation,convenient maintenance and high output torque at low speed.However,its noise problem has always been an important aspect affecting the quietness of ships.It is of great engineering significance to carry out noise analysis and control of diesel engine.In this thesis,the acoustic characteristics of radiated noise for a certain type of marine high-speed diesel engine are analyzed and the active-passive noise attenuation measures are taken according to its acoustic properties.Radiation noise and its identification tests are carried out at critical frequency.The radiation noise measurement experiment is performed with its emphasis on the 1/3 octave noise of diesel engine under the weight of A meter at the key frequencies,as well as the variation law of noise pressure level with the change of diesel engine speed.Sound pressure level distribution of noise generated by each part of diesel engine under the key frequency is measured in the noise source identification experiment in the measured plane,which provides guidance and reference for the subsequent active control of radiated noise.Then,a set of noise flexible and isolation panels for diesel engine is designed and installed according to the situation of experimental test rig.The reasonable utilization of controller,actuator and sensor for low frequency line spectrum radiation noise is a vital aspect of the active structural acoustic control test system for diesel engine noise enclosure.It provides a control system for active noise control of diesel engine noise enclosure through the writing and debugging of FxLMS adaptive active control algorithm in the LabVIEW software environment.It is found through the comparison of sound pressure spectrum measurement before and after opening the active control of diesel engine sound enclosure that the strong correlation of line spectrum of noise signal can be realized by using rotation speed as reference signal,and then the effective control of low-frequency line spectrum noise can be realized and the problems existing in the control process are discussed and analyzed.This work fully verifies the feasibility and effectiveness of the design scheme of active acoustic structural control for the noise enclosure of diesel engine.